En la cordillera Central de los Andes colombianos a la altura del departamento del Valle en las cabeceras del rio Cofre, en la inspeccion de El Rosario (municipio de Buga), se manifies- tan rasgos culturales arqueologicos, evidencias de ocupacion prehispanica cercana al momento del contacto con la invasion espanola. Las fuentes historicas de ese contacto hacen referencia a la “Sierra de los pijaos” o “Sierra alta de los pijaos”, como fronte- ra territorial vista desde las cronicas de las fundaciones de la ciudad de Buga, territorio vedado para los invasores espanoles, ocupado por grupos que hacian resistencia a la in- vasion. En el presente trabajo se da cuenta de exploraciones sobre la cuenca media del rio Guadalajara en la misma circunscripcion territorial, es decir la vertiente occidental de la cordillera Central. El caracter fronterizo de los asentamientos parece indicar que se tra- ta de dos patrones diferentes: el primero de ellos en El Rosario (que comparte semejanzas estilisticas con Chaparral–Tolima), y el segundo en El Janeiro, que tiene rasgos tardios dentro de lo que se conoce como Cauca Medio y Quimbaya. En este documento se rela- cionan exploraciones arqueologicas ineditas para esta region arqueologica colombiana. Palabras Clave: cordillera Central, Sierra de los pijaos, frontera, Valle del Cauca, asentamientos Tardios. Abstract In the Colombian Andean Central Range belonging to over the Department of Valle in the origins of Cofre river, at El Rosario (Municipality of Buga), there are certain cultural ar- chaeological characteristics that show the evidence of pre–Hispanic occupation, which occurred close to the moment of the first contact with the Spanish invasion. Historical sources of this contact make reference to the fact that the Central Mountain Range was called “Sierra de los pijaos” or “Sierra alta de los pijaos” and was considered the territorial limit since the foundation chronicles of the city of Buga. This is the same border that was used in those days, when Spanish invaders could not trespass due to the occupation of groups that were against the invasion. There is also information about explorations along the middle river stream Guadalajara –river in the same terri- torial limits; that is, the western branch of the Central Mountain Range. The fact that these establishments are found in the limits of the occupation might mean that the- re are two different patterns. The first one is El Rosario (which shares similarities in style with Chaparral– Tolima) and the second one is El Janeiro, which has late charac- teristics of what is known as Cauca Medio and Quimbaya. This document reports the unpublished archaeological explorations for this archaeological Colombian region. Keywords: central mountain range, Sierra de los Pijao, territorial limit, Cauca Valley, late settlements